Web unwind apparatus



Aug. 17, 1965 D. RYAN 3,201,057

WEB UNWIND APPARATUS Filed Aug. 1, 1963 7 Sheets-Sheet 1 INVENTOR DANAHEY R YAN ATTORNEY FIG. 1

D. RYAN WEB UNWIND APPARATUS Aug. 17, 1965 7 Sheets-Sheet 2 Filed Aug. 1, i963 INVENTOR DANAHEY RYAN ATTORNEY Aug. 17, 1965 D. RYAN 3,201,057

WEB UNWIND APPARATUS Filed Aug. 1, 1965 7 Sheets-Sheet 3 INVENTOR D ANA HEY RYAN BY (7am; Z42:

ATTORNEY 65 WW Q) 4% m m z'rl WEB UNWIND APPARATUS Filed Aug. 1, 1963 '7 Sheets-Sheet 4 Fla; 6

F1614 gi 6A VIIIIII llllll f/A f6 65 INVENTOR DANAHEY RYAN ATTORNEY Aug. 17, 1965 D. RYAN 3, 0 5

WEB UNWIND APPARATUS Filed Aug. 1, 1963 7 Sheets-Sheet 5 FIG. 5

INVENTOR DANA HEY R YA N ATTORNEY Aug. 17, 1965 0. RYAN 3, ,0

WEB UNWIND APPARATUS Filed Aug. 1, 1963 FIG. 7

7 Sheets-Shet e INVENTOR DANAHEY RYAN ATTORNEY FIG. 3;

United States Patent 3,201,957 WEB IJNWIND AlPARATUS Dauahey Ryan, Wilmington, Deh, assignor to E. 1. du Pont de Nernours and Company, Wilmington, Del., a corporation of Delaware Filed Aug. 1, 1963, Ser. No. 299,244 7 Claims. (@l. 242-581) This invention relates to web handling apparatus and, more particularly, it relates to apparatus for use in continuously unwinding web from separate spools.

During the production and handling of web-form materials it is frequently necessary or desirable to wind the unfinished web in spools or rolls prior to finally finishing or processing the web. In the manufacture of lightsensitive cine film, the film is generally wound on large spools prior to perforation, inspection, key numbering and rewinding on small spools of exact lengths. This requires a device capable of continuously unwindingthe unfinished film at a high rate of speed for introduction into the finishing process. The film should be fed at a constant tension but owing to its light-sensitive nature and general fragility great care must be taken which is not possibe with conventional web handling equipment. Since the device must operate in nearly complete darkness the operation should be as nearly automatic as possible with a minimum need for operator attention. i Further, when a spool is exhausted the device must be capable i of automatically initiating a splicing operation to a new appended claims, and is illustrated, in its preferred embodiments, in the accompanying drawings wherein:

FIG. 1 shows an elevation view of a general arrangement of the apparatus of the invention;

FIG. 2 shows a partial line 2- -2 of FIG. 1;

FIG. 3 is an enlarged sectional view of the turret supporting shaft assembly taken generally along line 3-4 of FIG. 2; FIG. 4 is a sectional plan view taken generally along View taken along line 44 of FIG. 7 is an enlarged elevation view of the turret shown in FIG. 1 with the follower arm assemblies shown in detail;

FIG. 8 is a setional view taken along line 8-8 of FIG. 7 showing the details of the follower arm assemb l FIG. 9 is an enlarged partial view of. the turret and related elements in the area adjacent the splicing mechanism;

FIG. 10 is an enlarged plan View of the camming face and related roll 85; i j

' FIG. 11 is a partial plan view taken along line 1.1-4.1 ofFIG. 9. j j i Referring to FIGS. 1, 2 and 3, the apparatus of this invention comprises essentially a circular, rotatable turret plate Ill on which are mounted two unwind spindle assemblies Ma and llb at opposite ends of the turret diameter. Each spindle assembly is complemented by an unwind follower arm 12 and dancer roll assembly 13 and 3,Zdl,ll5fl7 Patented Aug. 17, 1965 their associated elements, respectively. For purposes of simplifying the discussion, only spindle assembly 11a and its complementary apparatus are described in detail; however, it is to be understood that the spindle assembly lib and its complements are structurally and functionally identical. As can be seen in FIG. 1 the web 78 emerges from the apparatus in the direction of the arrow; suit able means (not shown) are provided to drive the web in this direction, e.g., positively driven wind-up rolls or the like.

As shown in the drawings, the turret assembly comprises a circular plate it) mounted at its axial center to a rotatable, hollow hub 14 which, in turn, is rotatably supported on a pair of spaced bearings 15a and 15b in a boxlike housing 16. The housing 16 is rigidly secured to the main machine frame designated generally by numeral 17.

Referring more particularly to FIG. 3, the hub 14 is shown to extend beyond the bearingslda and 15b at either end. Gne end is afiixed to the plate 10 and the other end is provided with a locking collar 18 that has two open slots 1% and 19b spaced apart and a pulley 26. Both the locking collar 18 and the pulley 2d are firmly keyed to the hub 14 for rotation therewith. Between the bearings lda and 15b inside the housing 16, a commercial slip ring assembly 21 (manufactured by the Breeze Corp.) is mounted on the hub 14 for rotation therewith.

The ring assembly 21 consists of a series of spaced electrically insulated disks 22 that have annular-shaped conductive rings 23 (see FIG. 4) on both faces. Four of the rings 23 are splitinto 180 arclengths while the re maiiiing four-teen rings have full 360' lengths.

In 4, each ring 23 is contacted by a brush 24 which is mounted in a brush holder 25 aflixed to the housing 16. The brush holder 25 carries a brush 24 which is electrica ly connected to one end of a power supply (not shown) which forms one-half of the electrical circuitry. The conductors forming the other half of this circuitry (not shown) are attached directly to the rings 23 inside the hub 14. The conductors are combined into a cable and emerge through an opening 26 in the hub 14 whereupon they connect to the various switch and load devices mounted on the turret assembly (not shown);

Shown inside the hollow hub 14 is a spindle drive shaft 27' rotatably mounted concentric with the hub 14 axis. l-ulleys 2-3 and 29 are fixed at the turret end of the shaft 27 and by means of timing belts 3i and 31, respectively, engage pulleys 49 on the spindle assemblies 11:: and 11b as shown in FIG. 5. The other end of the shaft 27 extends beyond the end of hub 14 and, as shown in FIG. 3, carries a pulley 32. The pulley 32 engages a timing belt 33 which engages a similar pulley 34 fixed to the shaft of a constant torque motor 35, shown in FIG. 2, which is securely mounted to the machine frame 17.

In FIG. 2, adjacent to the motor 35 and attached to the machine frame 17, is a speed reducer motor 35 to which is attached a pulley 37; by means of a tinting belt 3 8, the motor 36 is operatively connected to the pulley Ed on the hub ti-4- thus providing rotative power to the turret plate to be indexed 180. Referring to FIG. 3, the hub 1 may be locked in place by means of a dog 39 which enters either of the slots 19a or 1%; the dog it? is slidably journaled in a bracket 49 which is mounted to the housing id. The dog 39 abuts the spring 41 which functions to urge the tapered end of the dog 39 into engagement with either slot. The other end of the dog 39 is coupled by a pin 42 to the plunger 43 of a conventional solenoid (not shown) which, upon being energized, functions to withdraw the dog 39 from engagement with the slot in the collar 13.

Referring now to FIGS. 5 and 6, the spindle assemblies 11a and 1111 are described in detail below. As previously mentioned for simplifying the discussion, only spindle assembly 11a is discussed. The spindle 11a is an assemblage of rotating components contained in a hollow housing 44 mounted to the turret plate 1t). Within the housing 44 is a hollow shaft 45 rotatably supported on a pair of spaced frictionless bearings 45a and 45b and communicates on either end through the turret plate The portion of the shaft 45 on the front side of plate 1% is enlarged in diameter and has an open cavity. The other end of the shaft 45, passing through to the back side of the plate 1%, is coupled to a shaft 45 upon which is mounted a commercial, electrical clutch-brake mechanism 47 (manufactured by the Simplatrol Corporation) housed in an extension 45 of the housing -34. A pulley 49 is fixed to a rotating coil of the clutch portion of the clutchbrake 47 and is engaged by the belt 3-5 to the pulley 28 shown in FIG. 3. When the clutch coil (not shown) of the clutch-brake 47 is energized, the clutch is thus engaged and the brake coil (not shown) is de-energized and the brake is released; thus, the motor 35 is coupled to the shaft 45 and exerts a reverse torque on the shaft 45; i.e., the direction of the motor torque is such as to re sist the force of the unwind drive meaues which causes the withdrawal of web 73 from a core as secured to the shaft 45. If the web is not being withdrawn, the shaft 45 will rotate in the reverse direction until downstream web slack is taken up and the shaft 45, thereafter, will stand still until the web is moved by some agency other than the motor 35. If the clutch coil is tie-energized and the brake coil is energized, the pulley 49 and part of the clutch-brake 47 will rotate in the reverse direction under the urging of the motor 35; however, the shaft 45 will not rotate since it is restrained by the brake.

interposed between the bearings 45a and 45b is a non-conducting sleeve 50 affixed to the shaft 45 for rotation therewith. Metal bands 51 and 52 are embedded about the circumference of the sleeve 59 and are in rubbing contact with a pair of stationary brushes 53 and 54. The brushes 53 and 54 are juxtaposed in recesses in the housing 44 and are connected by insulated conductors (partially shown) to appropriate rings 23 of the slip ring assembly 21. At their inner end, the metal bands 51 and 52 are connected by insulated conductors to an indicator lamp 55 shown threadedly attached at the base of the enlarged portion of the shaft 45.

Concentric with the lamp 535 is a hollow adaptor 55 threadedly attached within a cavity in the end of shaft 45 thus forming an extension of the latter. As shown in FIG. 6B the external end of the adaptor 55 is modified by a cam contour having flat surfaces 57a and 57:) separated by protruding lugs. Engaging these surfaces is the split tang 58 portion (see FIG. 6A) of a hollow knob 59. The knob 59, in turn, is coupled to a flanged sleeve 66) which is slidably telescoped inside the hollow adaptor 56. A spring 51 which abuts the flange of the sleeve 60 and an internal shoulder in the adaptor 56 urges the tang 58 against the cam surfaces. A spring 62, anchored at one end to the knob 59 and at the other end to the adaptor 56, is interposed between the adaptor 56 and functions as a radially expandable means for frictional'ly chucking a spool or core 63. A series of holes (not shown) spaced circumferentially on the hollow adaptor 56 provide rough adjustment of the spring 62 diameter. The diameter is adjusted to be slightly less than the inside diameter of the core 63. This facilitates mounting and removal of a core as from the spindle assembly. The final incremental increase in the spring 9. diameter for frictionally engaging the core 63 is accomplished by manually rotating the knob 59. The cam surfaces 57a and 57b limit the angular rotation of the knob 59 and function to maintain the spring 62 in the contracted condition during loading or unloading, the spring 62 being wound so as to expand when tang 58 rests against cam surface 57b.

Referring to FIGS. 7 and 8, a follower arm assembly 12 on the face of the turret 10 is pivotally supported on a shaft 64. At its outer end, the follower arm 65 carries a roller 65 which is covered with an eiastomeric material which rides in contact with the outer periphery of a film roll 5% which is being unwound. One end of the pivot shaft 64 is attached to the arm 65 while the other end, on the back side of the plate 18, is attached a radially adjustable counterweight as which shares the hub with one link 69 of a 4-bar linkage system. The link 76 at the other end of the linkage system is gear-connected to the adjustable portion of a conventional variable autotransformer 71 which functions to control voltage in response to movement of the arm 65 and by that means, the torque output of the motor 35. In this manner the unwinding force exerted by the unwind drive means (not shown) is resisted to a varying amount depending upon the movement of arm 65. In carrying out this function, the follower arm assembly 12 thus serves to monitor film roll diameter as described below.

Referring to FIGS. '7, 9l1, the dancer roll assembly 13 consists of an arm 72 which is keyed to a shaft 73 which shaft is suitably journaled in the turret 10. On the back side of the turret 1d, the shaft 73 is keyed to a cam '74 that operatively engages cam follower 75 of a microswitch 76. On the extremity of the arm 72, a roller 77 is rotatably journaled to contact the web 7%; during operation. During a normal unwinding operation, the roller 77 is supported by a loop in the web as shown in FIG. 9; however, if the end of a film roll is reached or if the web '75 breaks for any reason (causing a loss in tension), then the arm '72 and dancer roll 77, will drop to the position 72 shown in phantom lines and the microswitch 7-6 will be actuated by the cam 74 and cam follower 75. This action results in other effects which are described below.

Referring to FIGS. 9, 10 and 11, a web guiding roll 79 is provided which is rotatably mounted in suitable antifriction bearings 150 on the main machine frame immediately to the right of the turret N. The roll 79 and its mounting are shown in FIG. 11 where it may be seen that the back end of the shaft 152 carries a pair of antifriction bearings 151 upon which is mounted a pulley, 153. 'The pulley 153 is engaged by a toothed belt 83 which also passes around adjustable pulley 85 (which is an idler), and pulley 154 on shaft 155, from which latter pulley 154 the belt 83 receives its power. In'FIG. 11 it may also be seen that the rear part 7% of the roll 79' has a larger diameter than the front part which latter is the portion the web 73 passes over. Similarly, the dancer roll 77 has a larger diameter section 77a to the rear of the section that engages the web. These enlarged sections 77a and 7% on the rolls are intended to come into contact with each other during a part of the time when the turret 10 is rotated, i.e., indexed from one position to an other. When this occurs the dancer rollassembly is substantially horizontal and the roll 77 is accelerated by the rolling contact between roll sections 77a and 79a. The bearings 151 were identified (above) as being of the antifriction type; however, despite the fact that these bearings roll on balls, some small amount of friction is pres ent. Therefore, when the pulley 153 is rotated (by the belt 83), the outer races of the bearings 151 will be rotated and then, by friction, the inner races will be rotated. Thus, power is transmitted to the roll 79 which is rotated at the desired web speed; the advantage of this type construction is that, if the web is subjected to an acceleration from some other source, the roll 79 is capable of following the change in web speed; howeyer, the torque exerted on the roll by the web will be slight and, therefore, the possibility of damage to the web surface (e.g., due to relative slippage) is considerably decreased.

Roller 84 is mounted on shaft 81 which is journaled in antifriction bearings in the turret 10; each roll is associated with a dancer roll assembly 13 and is situated in close proximity to roll 77. In back of the turret, the

86 is rigidly attached to the main machine frame 17 immediately to the right of the turret 1t and above the roll 79; this fixed cam 86 serves to support the dancer roll assembly 13 when the turret is indexing. The cam follower 87 behind roll 77 engages the inclined surface of the cam. 86 during only a part of the time that the turret 10 is in motion; during this time the cam follower 87-proceeds to run down the incline on the cam 86 until eventually it drops off; .at this stage the large portion 77a ofroll 77 comes in contact with the large portion 79a .of roll 79. Further rotation of the turret 1% allows the roll 77 to pass between rolls 79 and 84 to form the loop in theweb .78. This is further discussed below.

Referring to FIG. 11, roll 84 is mounted on antifriction bearings 156 which, in turn, are mounted on the shafti155'; this shaft 155 is power driven by pulley 157 by belt 153. The roll 84 is rotated at web speed by virtue of bearingfriction as described above for roll 79 with the same advantage.

Referring to FIG. 9., rolls 84 and 83 are associated witha web splicing device, known as a wiper-roll splicer, which is fully described in my copending US. application, Serial No. 167,583, filed January 22, 1962. Because of its gentle acceleration characteristics, this web splicer together with the web unwinding device being described hereinforms a preferred embodiment though it is recognized that other web splicing devices known in the art may be used. In general, it should: be realized that the nature of theoperations being carried out downstream of theunwind device and the splicer is'such that it is permissible. to, stop operations momentarily, upon the exhaustion of a supply roll, to allow time for splicing the expiringj or trailing end of one web roll to the leading end of a new roll; Thus, an on-the-fly type of web splicer is not required here; in general, any type splicer which is adapted to join the ends of two non-moving webs could be used. For use with the invention described herein, the wiper roll splicer is furnished with a slack takeup roll 159 as shown in FIG. 9 which is adapted to be driven in synchronism, at a 1-to-1 ratio, with the wiper roll 97 of the splicer by a means not shown. The slack take-up roll 159 turns clockwise as the .wiper 101197 and the web move to the left thus, the roll 159 helps to urge the Web to the left. 1

Referring particularly to FIG. 1,in operation, assume thata web 73 is being unwound from the lower of the twojspindles, denoted by 11b. The web 7%) runs from the bottomof the film roll 9%, up underneath roll 89,

over roll 79, underneath the roll 77 of the dancer roll assembly 13, above roll 84 around roll 88 and thence down to rolls 91 and 92 and on into some device (not shown) in which the web is being consumed at a subdriven by some unwind drive means (not shown) which V will exert the principal unwind force on the web 78.

,Many suitable means for effecting this force will be apparent to one skilled in the art. Theweb 7 8 is unwound from the spindle assembly 11b while the spindle assembly 11a at the upper portion of the turret It is inactive and is held in a braked condition by the clutch-break mechanism 47. i

A new sup-ply roll 90a is now mounted on the upper spindle assembly 11a and prepared for automatic splicing in the following manner. Assuming that the core 63 from some previous supply roll is still on the spindle, the operator manually removes it by pulling the knob 59 outward and rotating it clockwise. The tang 5% disengages from the cam surfaces 57b and enters cam sur face 57a thus causing the outside diameter of the torsion spring 62 to decrease, releasing the core 63.

If the web 7 3 is unexposed cine film it must be processed in a darkened environment; since the supply roll a is about twenty-four inches in diameter, the indicator lamp 55 in the-center of the hub provides a convenient means for assisting the operator in locating the spindle. Once the roll 96a is mounted, the operator reverses the knob 5% sequence causing the spring 62 to chuck or grip the core of the new supply roll.

The leading end of the new roll 9% is manually withdrawn from the roll and the new web 78' is passed over web guide roll 95, under roll 9-6, under the slack take-up roll 159 and thence to the top of roll 97 where it is manually secured by means of a piece of pressure sensitive tape. The manner in which the new web end/78' is secured to the roll 97 is fully described in U.S. application, Serial No. 167,583 (supra) and will not be repeated here. At this stage the new roll 9tla and the new web 73 are left in a static condition pending the exhaustion of the film roll 9615.

As the web 73 is unwound, the diameter of the roll 90b decreasesand this alters the load requirements on the torque motor 35. To compensate for this change so that constant tension of about one pound is maintained on the web 78, the follower arm assembly 12 monitors the nominal diameter of the roll 9%. As the diameter decreases, the arm assembly 12 pivots and shifts the 4-bar linkage (69 and 7%) which, in turn, change the voltage setting of the auto-transformer 71 that controls the motor 65.

When the tail end of the web 78 leaves the core 63 on the spindle assembly 11b, web tension is lost and the dancer roll assembly 13 then drops downward. This rotates the cam 74 which actuates switch 76 thus causing the machine to stop which causes the clutch-brake on lower spindle assembly 1112 to be actuated, i.e., to engage the brake and disengage the clutch while simultaneously activating the splicer. The knife on thesplicer then severs the web 73 between the rolls 84 and 88. At the instant of completion of this cut, the solenoid 43 is ener- 'gized and the dog 39 is retracted which unlocks the turret it); simultaneously, the speed reducer motor 36 energizes to cause the turret 10 to begin to index clockwise for and the clutch-brake on upper spindle asssembly 11a is energized to engage the clutch and disengage the brake.

"167,583 (supra) thus causing the web ends to be spliced together. In the. course of the splice cycle web slack is created which is taken up by reverse action of the spindlemotor 35. When the splicing sequence is COIII'. plete', the unwind drive means of the machine to which the web isbeing supplied .(not shown) starts to withdraw the spliced web 78 from the unwind and acceleratesthe web tofull speed during which time the turret plate 10 continues to index. As the turret approaches the 180 position, dancer roll assembly 13 and roll 81 come into proximity to roll 79. Roll 86 passes to the left of roll 79 while. the dancer arm 72 is restrained by the stationary cam 86 so that it eventually passes to the right of roll 79.

At the instant before these two elements pass roll 79 behind the machine, roll 81) is brought up to web speed by belt 83 and roll 77a is likewise brought up to web speed by contact with roll 79a. At this point, the web passes from the top of roll 79 to the top of roll 84 without being deflected. As the indexing of the turret continues beyond this point, the web 78 is deflected downward by roll 80 and as roll 77 (on dancer roll assembly 13) is released.

by the cam 86 and then by the roll 79 and passes between rolls 79 and 84, the web 78 is automatically threaded beneath the roll 77 to the position shown in FIG. 1. Spin- Z dle 11b is now in the upper position'of the turret plate It) and the empty core 63 can be manually removed by the operator and a new'supply roll put in position and prepared for splicing in the same manner previously described. When the turret reaches the 180 position, the dog 39 again locks it in position.

The unwinding apparatus of this invention is highly advantageous for handling light-sensitive cine film, particularly since such handle must occur in the virtual absence of light. Further, the automatic indexing of the turret in such a manner as to have the film from the fresh spool automatically positioned, i.e., in a loop beneath the second dancer roll, is a distinct advantage.

What is claimed is:

1. In a device for unwinding web from spools by the action of an unwind driving force the combination comprising a turret, a pair of rotatable spindles on said turret each adapted to receive a spool, unwind torque means for resisting the rotation of each spindle caused by said driving force, sensing means for sensing the decreasing diameter of web on a spool, control means responsive to said sensing means for reducing the resisting torque of said unwind torque means thereby maintaining constant tension in said web as it is being unwound, means for detecting the exhaustion of the web from a spent spool, said turret having indexing means for positioning a fresh spool into position for being unwound upon being actuated by said detecting means, and means for splicing of the trailing end of said web to the lead end of the web from the fresh spool when actuated by said detecting means.

2. In a device for unwinding web from spools by the action of an unwind driving force the combination comprising a turret, a rotatable spindle on said turret adapted to receive a web containing spool, unwind torque means for resisting rotation of said spindle caused by said driving force, sensing means for sensing the decrease in diameter of web being unwound from said spool, control means responsive to said sensing means for reducing the resisting torque of said unwind torque means thereby maintaining a constant tension in said web as it is being unwound, turret indexing means for moving a fresh spool into position for unwinding and means for detecting the exhaustion of web from said spool being unwound thereby initiating said indexing means.

3. In a device for unwinding web from spools by the action of an unwind driving force the combination comprising a turret, a pair of rotatable spindles on said turret adapted to receive first and second spools, a dancer roll supportable by the web being unwound from said first spool, actuating means in association with said dancer roll which is activatable by said dancer roll upon the discontinuance of said supporting web and turret indexing means for rotating said turret and thereby positioning said second spool into a position for being unwound, said indexing means being activatable by said actuating means.

4. A device as defined in claim 3 including means for splicing the trailing end of said web unwound from said first spool to the leading end of the web to be unwound from said second spool.

, 5. A device as defined in claim 3 including a stationary rotatable roller over which said unwound web travels from its spool before passing around the bottom of and supporting said dancer roll thereby forming a loop in said unwound web.

6. In a device for unwinding web from spools by the action of an unwind driving force the combination com prising a turret, a pair of rotatable spindles on said turret adapted to receive first and second spools, first and second dancer rolls on said turret, a stationary rotatable roller located adjacent said turret over which said web travels from said first spool before passing around the bottom of and supporting said first dancer roll, actuating means in association with said first dancer roll which is activatable by said first dancer roll upon the discontinuance of said supporting web, turret indexing means for rotating said turret responsive to exhaustion of the web from said first spool detected by said actuating means, means for supporting the web from said second spool above said stationary roller, and means for camming said second dancer roll away from said turret and stationary roller as the turret is indexed, the indexing movement bringing said second dancer roll down onto said web from said second spool thereby forcing it down on the top of said stationary roller but beneath and supporting said second dancer roll.

7. In a device for unwinding web from spools by the action of an unwind driving force the combination comprising (1) a turret, (2) a pair of rotatable spindles on said turret adapted to receive first and second spools, (3) a dancer roll supportable by the web being unwound from said first spool, (4) actuating means in association with said dancer roll which is activated by said dancer roll upon the discontinuance of said supporting web, (5) means for temporarily stopping the movement of said web, (6) means for severing the trailing edge of the web unwound from said first spool, (7) turret indexing means for rotating said turret thereby moving said second spool into position for being unwound, and (8) splicing means for splicing said trailing endof said web unwound from said first spool to the leading end of the web to be unwound from said second spool, said means (5), (6), (7) and (8) being activatable by said actuating means (4).

References Cited by the Examiner UNITED STATES PATENTS Caifrey 24258.3

DONALD W. PARKER, Primary Examiner.

MERVIN STEIN, Examiner, 

1. IN A DEVICE FOR UNWINDING WEB FROM SPOOLS BY THE ACTION OF AN UNWIND DRIVING FORCE THE COMBINATION COMPRISING A TURRET, A PAIR OF ROTATABLE SPINDLES ON SAID TURRET EACH ADAPTED TO RECEIVE A SPOOL, UNWIND TORQUE MEANS FOR RESISTING THE ROTATION OF EACH SPINDLE CAUSED BY SAID DRIVING FORCE, SENSING MEANS FOR SENSING THE DECREASING DIAMETER OF WEB ON A SPOOL, CONTROL MEANS RESPONSIVE TO SAID SENSING MEANS FOR REDUCING THE RESISTING TORQUE OF SAID UNWIND TORQUE MEANS THEREBY MAINTAINING CONSTANT TENSION IN SAID WEB AS IT IS BEING UNWOUND, MEANS FOR DETECTING THE EXHAUSTION OF THE WEB FROM A SPENT SPOOL, SAID TURRET HAVING INDEXING MEANS FOR POSITIONING A FRESH SPOOL 